This invention relates to lathes of the kind in which bar stock is fed progressively through a collet which is actuated to grip the stock to allow production of workpieces one after another from the protruding end of the bar. The invention is moreover applicable to single or to multi spindle lathes.
Bar feed mechanisms which have been proposed and used include discs for feeding the bar through the machine by rotation of the discs. Relative rotation between the discs and the bar stock produces damage to the surface of the bar stock, when the disc surfaces are hard, though where the disc surfaces are soft to overcome this, the disc surfaces themselves become damaged by contact with burrs or other projections on the bar. Such burrs or projections are particularly to be found at the bar ends. This problem is particularly acute in machines having apparatus by means of which the bar is overfed and subsequently pushed backwards against the direction of rotation of the discs.